In the disclosure of the present invention reference is mostly made to the treatment of diabetes by delivery of insulin, however, this is only an exemplary use of the present invention.
Drug Injection devices have greatly improved the lives of patients who must self-administer drugs and biological agents. Drug Injection devices may take many forms, including simple disposable devices that are little more than an ampoule with an injection means or they may be durable devices adapted to be used with pre-filled cartridges. Regardless of their form and type, they have proven to be great aids in assisting patients to self-administer injectable drugs and biological agents. They also greatly assist care givers in administering injectable medicines to those incapable of performing self-injections.
Performing the necessary insulin injection at the right time and in the right size is essential for managing diabetes, i.e. compliance with the specified insulin regimen is important. In order to make it possible for medical personnel to determine the effectiveness of a prescribed dosage pattern, diabetes patients are encouraged to keep a log of the size and time of each injection. However, such logs are normally kept in handwritten notebooks, from the logged information may not be easily uploaded to a computer for data processing. Furthermore, as only events, which are noted by the patient, are logged, the note book system requires that the patient remembers to log each injection, if the logged information is to have any value in the treatment of the patient's disease. A missing or erroneous record in the log results in a misleading picture of the injection history and thus a misleading basis for the medical personnel's decision making with respect to future medication. Accordingly, it may be desirable to automate the logging of ejection information from medication delivery systems.
Though some injection devices integrate this monitoring/acquisition mechanism into the device itself, e.g. as disclosed in US 2009/0318865 and WO 2010/052275, most devices of today are without it. The most widely used devices are purely mechanical devices either durable or prefilled. The latter devices are to be discarded after being emptied and so inexpensive that it is not cost-effective to build-in electronic data acquisition functionality in the device it-self. Correspondingly, data acquisition/monitoring functionality have been proposed to be provided in a separate device to be put on or in the injection device, i.e. some kind of accessory e.g. an add-on module to the injection device.
For example, WO 2010/098927 discloses a medical module which is configured to be attached to a drug delivery pen, the module being adapted to detect and store selected and ejected dosages as well as other data. Further arrangements adapted to capture dose data are known from WO 2010/128493, EP 2 060 284, WO 2008/037801 and WO 2010/052275.
Injection devices that provide spring assisted drug expelling are becoming increasingly popular. However, for spring driven devices it is a challenging task to develop adequately performing electronic capturing systems that reliably monitor movements during expelling of a drug. Hence, expensive and more complex electronic dose capturing systems are required. US 2011/0301534 and U.S. Pat. No. 4,921,487 disclose spring driven delivery devices that include speed regulation means which are incorporated for ensuring a particular expelling drug rate. US 2011/077595 includes disclosure of various braking mechanisms for protecting the mechanism of the device against inadvertent operation that potentially would damage the mechanism.
Having regard to the above, it is an object of the present invention to provide systems and methods supporting simple and reliable yet cost- and energy-effective detection and storage of dose data related to use of a drug delivery device.